Some 20-thousand unionized tower crane operators launched a nationwide strike on Tuesday, demanding wage increases and a ban on the use of small-sized tower cranes. 

With the strike, the operation of roughly 23-hundred tower cranes have come to a halt. 

According to the Korean Confederation of Trade Unions and the Federation of Korean Trade Unions, that figure accounts for some 70 percent of tower cranes in all of the nation’s construction sites. 

Among the workers' demands are a seven percent increase in pay, greater flexibility regarding summer vacations and eased regulations on setting up resting spaces at construction sites.

Ahead of the strike, the unionized operators began a rally atop some tower cranes on Monday afternoon, interrupting work at both residential and commercial construction sites.