Washington, Oct 11 (IANS): The US takes security on the Korean Peninsula and its alliance with South Korea "very seriously", a Pentagon spokesperson has said, after North Korea said it would cut off all roads and railways linked to South Korea and fortify defence along the inter-Korean border.

Pentagon Press Secretary Maj. Gen. Pat Ryder made the remarks on Thursday as North Korea has notified the South Korea-based UN Command (UNC) of such a plan at a time of "tensions caused by its continued launches of trash balloons to the South and tough rhetoric", Yonhap news agency reported.

"When it comes to the security on the peninsula and our alliance with South Korea, that's something that we obviously take very seriously," he told a press briefing.

He was responding to a reporter's question about North Korea having informed the UNC of its military decision without informing South Korea of the measure. UNC is an entity that oversees activities in the Demilitarized Zone separating the two Koreas.

"We maintain frequent communications with our Republic of Korea allies. As for why the DPRK may choose to do something as it relates to communicating items like that, I refer you to them," he said.

The Republic of Korea is South Korea's official name. DPRK stands for North Korea's official name, the Democratic People's Republic of Korea.

"Regardless, we have a very strong alliance with South Korea and will continue to work together towards security and stability throughout the region," he added.

Asked if there have been any signs of military cooperation between North Korea and Iran, Ryder said that he has not seen anything to indicate the two countries' cooperation.

"But obviously, (it is) something that we'll continue to keep a close eye on," he said.