SEOUL, South Korea (AP) — Ending a global guessing game on when and where they would meet, North Korean leader Kim Jong Un and Russian President Vladimir Putin got together at a rocket launch facility in the Russian Far East on Wednesday for their first summit in four years.

The talks between the isolated, nuclear-armed leaders lasted for more than four hours and focused on expanding the military cooperation of two countries in intensifying confrontations with the West.

The decision to meet at Vostochny Cosmodrome, a major satellite launch facility, may communicate what Kim sees as the crucial next steps in his efforts to build a viable nuclear arsenal that could threaten the United States and its allies in Asia.

With the ability to dangle vast stockpiles of munitions that Putin likely covets for his war in Ukraine, Kim in exchange may have sought badly needed economic aid and sophisticated weapons technologies to advance his military nuclear program, experts said in advance of the meeting.

Kim also may have pushed for Russian technology transfers on military reconnaissance satellites, an asset on his weapons wish list that he has struggled to acquire. The group of military officials Kim chose for the trip also hints that the North may seek technologies related to missiles and nuclear-capable submarines.

But it remains unclear whether Russia would be willing to share such sensitive technologies for what could easily end up being a limited amount of North Korean ammunition slowly delivered through the small land link between the countries.

A look at Kim’s growing arsenal and areas where he might possibly seek Russian help:

SPY SATELLITES

Kim’s visit to Russia came after North Korea experienced repeated failures in recent months to put its first military spy satellite into orbit. The country has vowed to make a third try for the spy satellite in October.

But there are questions over whether its newly developed satellite would be sophisticated enough to support its stated goals of monitoring detailed U.S. and South Korean military movements in real-time and processing and transmitting high-resolution images.

After retrieving and studying the wreckage following North Korea’s first launch failure in May, South Korea’s military concluded the device wasn’t advanced enough to conduct military reconnaissance from space as the North claimed.

The North Korean delegation in Russia included Pak Thae Song, chairman of the country’s space science and technology committee that handles the spy satellite project, a possible indicator that Kim was seeking to secure Russian assistance in developing such systems.

Spy satellites are among an array of major weapons systems Kim publicly vowed to develop during a major political conference in 2021.

Kim has used the international distraction caused by Putin’s war on Ukraine to ramp up his weapons demonstrations, test-firing more than 100 missiles since the start of 2022, including two short-range launches toward the sea on Wednesday.

Kim has also punctuated his testing activity with an escalatory nuclear doctrine that authorizes his military to conduct preemptive nuclear attacks against enemies if it perceives Pyongyang’s leadership as under threat.

Space-based reconnaissance capabilities would potentially enhance the threat posed by Kim’s missiles.

While examining the North’s spy satellite at the country’s aerospace agency in April, weeks before its first failed launch, Kim said the device would allow his forces to “use “pre-emptive military force when the situation demands.”

After repeated failures, North Korea successfully put its first satellite into orbit in 2012, and the second one in 2016, but experts say there has been no evidence that both satellites have ever transmitted imagery back to North Korea.

The U.N. Security Council imposed economic sanctions on North Korea over its previous satellite launches, seeing them as covers for long-range ballistic missile tests.

Asked whether Russia would help North Korea build satellites, Putin was quoted by Russian state media as saying “That’s why we have come here. The DPRK leader shows keen interest in rocket technology. They’re trying to develop space, too.” He used the abbreviation for North Korea’s formal name, the Democratic People’s Republic of Korea.

Kim told Putin he was “honored to be given the opportunity to engage in a conference at a space launch facility and gain deeper understanding of the current state and future of a space power nation.”

INTERCONTINENTAL BALLISTIC MISSILES

Kim’s space ambitions are likely tied to his efforts to develop more powerful intercontinental ballistic missiles that are designed to reach the U.S. mainland, since space-launch rockets share the same core technologies with those weapons, experts say,

Some of North Korea’s ICBM tests in recent months that the country claimed as tests of satellite launch and payload technologies were also seen as part of efforts to develop missiles that can deliver multiple warheads toward different targets, improving their chances of evading missile defenses.

This year, North Korea flight-tested its most advanced missile yet, a solid-propellant ICBM called the Hwasong-18, which demonstrated a potential range to reach deep into the U.S. mainland.

North Korea’s previous ICBMs use liquid fuel that must be added relatively close to the launch, and they cannot remain fueled for prolonged periods. An ICBM with built-in solid propellants would be easier to move and hide and can be fired more quickly, reducing the opportunities for opponents to detect and counter the launch.

Although North Korea’s ICBMs have demonstrated impressive potential range, it’s unclear if the country has acquired the technology to ensure that the warheads would survive the harsh conditions of atmospheric reentry to strike targets. Some experts suspect that’s an area where the North might ask for Russian help.

While all of North Korea’s ICBMs have launched at a near straight-up angle to avoid the territory of neighboring countries, a functioning spy satellite could inspire the North to flight-test the missiles at normal ballistic angles across the Pacific Ocean. Doing that would allow the North’s scientists and engineers to gather launch data from remote locations, according to some experts.

SUBMARINES

Some analysts say Kim may also want Russian help in developing ballistic-missile submarines and nuclear propulsion submarines. He has traveled to Russia with the top commander of his navy, Admiral Kim Myong Sik.

Kim attended a ceremony last week at a military shipyard in eastern North Korea, where the country unveiled a purported nuclear attack submarine that it said could launch tactical nuclear weapons from underwater. South Korea’s military expressed doubt the submarine, which was the result of reshaping an existing submarine to install 10 launch tubes, would be useful operationally.

In recent years, North Korea tested a variety of missiles designed to be fired from submarines. In theory, such capacity would bolster its deterrent by ensuring a survivable capability to retaliate after absorbing a nuclear attack on land.

Still, it would take considerable time, resources and technological improvements for the heavily sanctioned nation to build a fleet of at least several submarines that could travel quietly and execute attacks reliably, analysts say.

During last week’s event, Kim reiterated his goals of acquiring nuclear-propelled submarines, which can quietly travel long distances and approach enemy shores to deliver strikes. However, analysts say such capacities would likely be unfeasible for North Korea without external assistance.

CONVENTIONAL WEAPONS

Some analysts question whether Russia, which has always closely guarded its most important weapons technologies, even from key partners like China, would be willing to share them with North Korea.

South Korea’s Institute for National Security Strategy, a think tank run by Seoul’s main spy agency, said in a report last week that the military cooperation between Moscow and Pyongyang was more likely to center around conventional capabilities.

Russia could possibly help North Korea improve its badly aged air force that remains reliant on fighter jets sent by the Soviet Union in the 1980s or provide anti-aircraft missiles to strengthen the North’s defense, the institute said.

After meeting with Kim on Wednesday, Putin said the North Korean leader would continue his visit by flying to the Far East cities of Vladivostok and Komsomolsk-on-Amur. Workers were seen constructing a temporary wooden platform at a railway station in Komsomolsk-on-Amur, where Putin said Kim planned to tour an aircraft plant.