A Japanese F-15 fighter jet lost part of its air-to-air missile while making an emergency take-off to intercept an aircraft, local media reported.

The F-15 was taking off at the Japan Air Self-Defense Force (JASDF) base in Chitoseon on May 5 when one of the missile blades dropped off mid-flight, NHK News reported on Thursday.

The fighter jet was reportedly scrambled for an alert mission to intercept an unidentified aircraft.

The lost part is said to be 45cm in length, weighing 4.5kg.

Japanese Air Force jets have intensified their activities amid the ongoing Korean Peninsula crisis. In recent months, Japan’s F-15s have taken part in multiple aerial exercises run by the US command in Asia-Pacific.

There are currently over 150 F-15s in the JASDF fleet, assembled by Mitsubishi Heavy Industries. The air force expects 40 F-35 fifth-generation fighters to come into service within the next years.

Earlier, Japan signed a major arms deal with its main ally, the US, to purchase 56 advanced medium-range AIM-120C-7 air-to-air missiles from Raytheon.

READ MORE: Japan to upgrade 200 F-15 jets, doubling missile payload amid E. China Sea tensions

The deal, worth $113 million, will “provide Japan a critical air defense capability to assist in defending the Japanese homeland and US personnel stationed there,” the Defense Security Cooperation Agency (DSCA) said in a statement on Wednesday.

The arms deal, pending approval by the US Congress, comes at the request of the Japanese government.

Missiles aside, it includes containers, weapons support and support equipment, spare parts, US government and contractor engineering, as well as technical and logistical support services.

The Japanese military scrambled fighter jets 1,168 times during the fiscal year 2016, which ended in March 2017, the Japan Times reported. The number is the highest on record since 1958.

Of the scrambles, 851, or 73 percent, were to counter Chinese aircraft, 280 more than in the previous fiscal year, the newspaper wrote.