SEOUL, South Korea (AP) — US Defence Secretary Lloyd Austin on Tuesday said the United States will increase its deployment of advanced weapons such as fighter jets and bombers to the Korean Peninsula as it strengthens joint training and operational planning with South Korea in response to a growing North Korean nuclear threat.

Austin made the comments in Seoul after he and South Korean Defence Minister Lee Jong-Sup agreed to further expand their combined military exercises, including a resumption of live-fire demonstrations, and continue a “timely and coordinated” deployment of US strategic assets to the region, according to their offices.

Austin and Lee also discussed preparations for a simulated exercise between the allies in February aimed at sharpening their response if North Korea uses nuclear weapons.

Austin’s trip comes as South Korea seeks stronger assurances that the United States will swiftly and decisively use its nuclear capabilities to protect its ally in face of a North Korean nuclear attack.

South Korea’s security jitters have risen since North Korea test-fired dozens of missiles in 2022, including potentially nuclear-capable ones designed to strike targets in South Korea and the US mainland.

South Korea and the United States have also been strengthening their security cooperation with Japan, which has included trilateral missile defence and anti-submarine warfare exercises in past months amid the provocative run in North Korean weapons tests.

In a joint news conference following their meeting, Austin and Lee said they agreed that their countries’ resumption of large-scale military drills last year, including an aerial exercise involving US strategic bombers in November, effectively demonstrated their combined capabilities to deter North Korean aggression.

The allies had downsized their training in recent years to create room for diplomacy with North Korea during the Trump administration and because of the COVID-19 pandemic.

“We deployed fifth-generation aircraft, F-22s and F-35s, we deployed a carrier strike group to visit the peninsula, you can look for more of that kind of activity going forward,” Austin said.

He said the US commitment to protecting its allies with its full range of military capabilities, including nuclear ones, remains “ironclad.”

North Korea’s ramped-up missile tests have been punctuated by threats to preemptively use its nuclear weapons in a broad range of scenarios in which it perceives its leadership to be under threat, including conventional clashes or non-war situations.