China and South Korea agreed on Monday to slap tougher sanctions on North Korea if it carries out nuclear or long-range missile tests, a senior official in Seoul said, as a U.S. Navy strike group headed to the region in a show of force.

North Korea marks several major anniversaries this month and often marks the occasions with major tests of military hardware.

The possibility of U.S. military action against North Korea in response to such tests gained traction following last week’s strikes against Syria. Previously, Washington has leaned toward sanctions and pressure to deter North Korea, butthat position may be hardening.

No military options

However, South Korea’s chief nuclear envoy Kim Hong-kyun said there was no mention of any military option in his talks with China’s Special Representative for Korean Peninsula Affairs, Wu Dawei. The two also did not discuss any possible strike against the North by the Trump administration.

“Both sides agreed that despite the international community’s warnings, if North Korea makes strategic provocations such as a nuclear test or an ICBM launch, there should be strong additional measures in accordance with UN security council resolutions,” Mr. Kim told reporters.