Chinese President Xi Jinping’s allusion to boosting military ties with North Korea this week has raised the specter of deeper security cooperation between the long-time allies, including closer coordination on a Taiwan contingency.

During a summit with Kim Jong Un in Pyongyang, Xi called for improving ties in the fields of diplomacy, law enforcement and the military. China’s defense minister also participated in the talks, marking the first time a Chinese defense chief has visited North Korea in 17 years.

But readouts from the two sides offered no specifics about what future military cooperation might look like, leaving more questions